Out of 31 COVID-19 cases caused by the variant detected in the United States as of Dec. 3, the vaccination status of 22 people is known. Of those, 15 were vaccinated.
Omicron is a new strain that experts say may transmit more easily than earlier variants. There are also early indications that it can better evade immunity provided by prior infection, and concern that vaccines may not provide as much protection against it.
One of the cases in the United States so far was confirmed to have recovered from COVID-19 and have natural immunity.
Authorities haven’t disclosed the vaccination status of nine people, including seven in New York, one in Pennsylvania, and one in Missouri. New York and Missouri officials declined to give updates on Sunday while Pennsylvania officials did not return a request for comment.
Cases caused by the Omicron variant also have been detected in California, Colorado, Hawaii, Maryland, Minnesota, Nebraska, New Jersey, and Utah.
Many of the patients either returned recently from Africa, where the variant was first identified last month, or came into close contact with somebody who had.
“We absolutely have community spread in this country,” Dr. Anthony Fauci, the longtime director of the National Institute of Allergy and Infectious Diseases, said on Bloomberg TV on Dec. 3. “We don’t know how many of them, but there’s no doubt there’s community spread.”
However, the dominant variant in the country is still Delta, Centers for Disease Control and Prevention (CDC) Director Dr. Rochelle Walensky told reporters during a virtual briefing around the same time.
“I know that the news is focused on Omicron, but we should remember that 99.9 percent of cases in the country right now are from the Delta variant. Delta continues to drive cases across the country, especially in those who are unvaccinated,” she said.
Health authorities are sticking to the same advice they have been giving since Omicron emerged, telling Americans to get vaccinated and get booster shots since the vaccines’ protection against infection drops sharply over time.
The bulk of studies and real-world data suggest that protection bestowed by prior infection is superior to that of vaccines, but scientists are concerned the Omicron variant may change that calculus.
Surveillance data from South Africa, researchers there said last week, points to the variant evading natural immunity better than the Delta and Beta strains.
The systems from which the data was pulled didn’t list people’s vaccination status, making it impossible to ascertain whether the strain can also beat vaccines better, researchers said.
“Although we haven’t proven it yet, there’s every reason to believe that if you get vaccinated and boosted that you would have at least some degree of cross-protection, very likely against severe disease, even against the Omicron variant,” Fauci told reporters on Dec. 3.
Update: The number of known Omicron variant cases has been updated.